ci: add code coverage workflow

Author: noahjoeris

.github/workflows/code_coverage.yml

@@ -0,0 +1,41 @@
+name: Code Coverage
+
+on: [push, pull_request]
+
+permissions: {}
+
+jobs:
+  Codecov:
+    name: Code Coverage
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Install lcov tools
+        run: sudo apt-get install lcov -y
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@v1
+        with:
+          toolchain: nightly
+          components: llvm-tools-preview
+      - name: Rust Cache
+        uses: Swatinem/rust-cache@v2
+      - name: Install cargo-llvm-cov
+        run: if [[ ! -e ~/.cargo/bin/cargo-llvm-cov ]]; then cargo install cargo-llvm-cov; fi
+      - name: Make coverage directory
+        run: mkdir coverage
+      - name: Test and report coverage
+        run: cargo +nightly llvm-cov -q --doctests --branch --all --ignore-filename-regex "(example*)" --all-features --lcov --output-path ./coverage/lcov.info
+      - name: Generate HTML coverage report
+        run: genhtml -o coverage-report.html --ignore-errors unmapped ./coverage/lcov.info
+      - name: Coveralls upload
+        uses: coverallsapp/github-action@master
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-report
+          path: coverage-report.html